Smart card contact mechanisms generally comprise one of two types:
1. a sliding contact mechanism. PA1 2. a landing contact mechanism. PA1 Selinki U.S. Pat. No. 3,917,372, issued Nov. 4, 1975 PA1 Moreno U.S. Pat. No. 4,404,464, issued Sep. 13, 1883 PA1 Simamura et al. U.S. Pat. No. 4,724,310, issued Feb. 9, 1988 PA1 Bertrand et al. U.S. Pat. No. 4,443,049, issued Apr. 17, 1984 PA1 Chalendard U.S. Pat. No. 4,795,897, issued Jan. 3, 1989 PA1 Bleier et al. U.S. Pat. No. 4,932,889, issued Jun. 12, 1990
In this type of mechanism a set of spring-loaded contact members extending into the card slot contact the leading edge of the inserted smart card and slide along the surface of the card until the card reaches the read position with the contact members resting on the corresponding contact pads of the smart card. U.S. Pat. No. 4,675,516 illustrates this type of mechanism. PA2 In this type, spring-loaded contact members face the card slot, but are initially spaced away from the smart card as it is inserted, and some form of mechanism causes the contact members to move toward the smart card and particularly the contact pads of the smart card as it is further inserted into the card slot, and during the final phase of smart card insertion, brings the contact members of the reader/writer come contact with the contact pads with a combined landing and wiping action as the spring-loaded contact members compress.
While type 1 is a less expensive contact mechanism, it tends to be less reliable since it is wiping across a much longer surface of the smart card and thus more susceptible to picking up contaminants that could preclude making good electrical contact with the smart card contact pads. In addition, it results in more contact wear and more wear of the contact pads of the smart card. Thus, this type of contact mechanism is generally limited to smart card applications in which the smart card is only infrequently inserted and removed, e.g. in cellular telephone systems or transaction terminals applications in which the smart card performs a security function and generally remains mounted in the reader/writer device.
Type 2 is preferred in reader/writer device applications in which insertion and removal of a smart card is anticipated to occur dozens and, in some cases, hundreds of times per day, e.g. in electronic purse applications of ATMs and transaction terminals.
Prior art landing contact mechanisms tend to be complex mechanisms, and generally involve either a linear ramping movement or a pivoting movement to land the reader/writer contact set onto contact pads on the smart card as the smart card is inserted into a card slot. In some cases the card itself actuates the landing contact mechanism. In other cases, the card moves a carriage or frame which actuates the landing contact mechanism.
The following U.S. Patents are illustrative of prior art landing contact mechanisms in which the card or other portable device cause translation of a carriage or frame which, in turn operates the landing contact mechanism:
The following U.S. Patents are illustrative of prior art landing contact mechanisms in which the leading edge of the inserted smart card directly operates the landing contact mechanism to cause the reader/writer contact set to land on the smart card contact pads:
Other types of prior art landing contact mechanisms are illustrated in the following patents:
Murschall U.S. Pat. No. 4,743,746, issued May 10, 1988, utilizes a pivoting card slot defining frame with a card contact pad window therein so that the frame and smart card a are both manually pivoted into contact with a stationary set of reader/writer contact fingers. In other words, the smart card contact pads land on the contact fingers of the reader/writer device which is the reverse of landing the reader/writer contact fingers on the contact pads of the smart card.
Ohtsuki et al U.S. Pat. Nos. 4,843,221 and 4,931,622, utilize a reader/writer contact set carried on a pivoting card latch arm so that the contact set pivots away from the smart card surface as the leading edge of the card raises the latch head of the latch arm and then pivots back into contact with the smart card contact pads when the latch head of the latch arm falls back behind the trailing edge of the smart card after full insertion.
It is known in the art to combine a landing contact mechanism with a card latch mechanism which retains the smart card in the read position after insertion to make sure that the card is not prematurely withdrawn by the cardholder during operation of the reader/writer system. The Ohtsuki et al. patents referred to above directly integrate the card latch mechanism with the reader/writer landing contact mechanism, but require a complex card ejecting mechanism to partially eject an inserted smart card after the card latch is released.
The Murschall Patent discussed above also has a card latching feature which utilizes a catch projection on the stationary frame near the card entry location so that the trailing edge of the smart card is pushed under this lip by a compression spring at the forward end of the card slot after card and frame are pivoted into the card read position and then released. This slight backward movement of the smart card under the lip is relied upon for contact wiping action.
Other card latching devices are illustrated in Kilborn U.S. Pat. No. 4,527,052 and Hansbauer U.S. Pat. No. 4,734,567 and Sugino et al. U.S. Pat. No. 5,196,687.